Gonadotropin and steroid hormones regulate pluripotent very small embryonic-like stem cells in adult mouse uterine endometrium

Abstract

BackgroundVery small embryonic-like stem cells (VSELs) exist in adult organs, express pluripotent markers and have the ability to differentiate into three germ layers in vitro. Testicular, ovarian and hematopoietic stem/progenitor cells express receptors for follicle stimulating (FSH) and ovarian hormones and are activated by them to undergo proliferation/differentiation. VSELs exist in mouse uterus and are regulated by physiological dose of estradiol (E) & progesterone (P) during endometrial growth, differentiation and regeneration/remodeling. In the present study, effects of daily administration of E (2 μg/day), P (1 mg/Kg/day) or FSH (5 IU/day) for 7 days on the endometrium and stem/progenitor cells was studied in bilaterally ovariectomized mice.ResultsE treatment resulted in hypertrophy whereas P resulted in hyperplasia and overcrowding of epithelial cells. FSH also directly stimulated the endometrial cells. Nuclear OCT-4A positive VSELs were visualized in ovariectomized (atrophied) endometrium and cytoplasmic OCT-4B positive epithelial, stromal and endothelial cells were observed after treatment. FSH treated uterine tissue showed presence of 4 alternately spliced FSHR isoforms by Western blotting. 3–5 μm VSELs with a surface phenotype of LIN-/CD45-/SCA-1+ were enumerated by flow cytometry and were found to express ER, PR, FSHR1 and FSHR3 by RT-PCR analysis. Differential effects of treatment were observed on pluripotent (Oct4A, Sox2, Nanog), progenitors (Oct-4, Sca-1), primordial germ cells (Stella, Fragilis) and proliferation (Pcna) specific transcripts by qRT-PCR analysis. FSH and P (rather than E) exerted profound, direct stimulatory effects on uterine VSELs. Asymmetric, symmetric divisions and clonal expansion of stem/progenitor cells was confirmed by co-expression of OCT-4 and NUMB.ConclusionsResults confirm presence of VSELs and their regulation by circulatory hormones in mouse uterus. Stem cell activation was more prominent after P and FSH compared to E treatment. The results question whether epithelial cells proliferation is regulated by paracrine influence of stromal cells or due to direct action of hormones on stem cells. VSELs expressing nuclear OCT-4A are the most primitive and pluripotent stem cells, undergo asymmetric cell division to self-renew and differentiate into epithelial, stromal and endothelial cells with cytoplasmic OCT-4B. Role of follicle stimulating and steroid hormones on the stem cells needs to be studied in various uterine pathologies.

Further characterization of adult sheep ovarian stem cells and their involvement in neo-oogenesis and follicle assembly

“…Our results demonstrate that in both testes [ 17 ] and ovaries [ 11 ], FSH exerts its action on the stem/germ cells via alternatively spliced Fshr3 receptor which gets more up-regulation compared to Fshr1. Using the same FSHR antibody raised against exon 2 which is conserved in alternately spliced isoforms, we recently detected all the 4 FSHR isoforms in mouse uterus [ 56 ].…”

Generation of a hTERT-Immortalized Human Sertoli Cell Model to Study Transporter Dynamics at the Blood-Testis Barrier

“…Western blot analysis indicated a negligible difference in FSHR expression between both cells ( Figure 3 B), which was expected due to minor differences in mRNA expression ( Figure 3 A and Figure S2 ). Additional lighter bands for FSHR at 20, 30, and 40 kDa were noted and attributed to splice variants of the protein [ 42 , 43 , 44 ]. Similarly, there were inconsequential differences in protein expression of AR, supported by minimal changes to mRNA expression ( Figure 3 A,C and Figure S2 ).…”

Similar Population of CD133+ and DDX4+ VSEL-Like Stem Cells Sorted from Human Embryonic Stem Cell, Ovarian, and Ovarian Cancer Ascites Cell Cultures: The Real Embryonic Stem Cells?

“…A population of small stem cells showing pluripotency persists from the embryonic period of life in adult human tissues and organs, such as bone marrow, umbilical cord blood and peripheral blood, and are termed very small embryonic-like stem cells (VSELs). These cells were first discovered by the research group of Ratajczak [1,2] and further explored by several other groups in bone marrow [3,4,5,6,7,8], umbilical cord blood [9,10,11,12], peripheral blood [13,14], uterine endometrium [15], testis [16], retina [17] and bone [18] in humans and rodents. VSELs are proposed to originate in the embryonic epiblast during development [19,20], mobilized into the peripheral blood under inappropriate conditions (e.g., stroke, myocardial ischaemia, skin burn injury, septic shock, brain injury, Crohn’s disease) to regenerate the tissues and organs [21,22,23,24,25,26], and proposed to be able to regenerate organs, such as the pancreas, brain, lung, liver or heart, by transplantation [27,28,29,30,31].…”